In order to maintain and/or improve product yield on a manufacturing line for semiconductor substrates, thin film substrates, or the like, it is necessary to inspect defects existing on the surfaces of semiconductor substrates, thin film substrates, or the like.
To detect minute defects on sample surfaces, a method of detecting defects having dimensions of tens of nm to several μm or more is available, for example. The method consists of irradiating a wafer surface with a focused laser beam and gathering and detecting light scattering from defects.
JP-A-2008-20374 (Patent Literature 1) is available as a background art technique of the present technical field. Disclosed in this publication is “a defect inspection device or tool comprising a light source means emitting a laser in pulsed operation, an irradiation optical system means for controlling the state of polarization of the laser emitted from the light source means and directing the laser at a sample, a detection means for detecting light reflected and scattered from the sample, and a signal processing means for processing a detected signal detected by the detection means and detecting defects on the sample” (refer to the claims).
Defects referred to herein include particles (foreign matter) adhering to wafers, crystal originated particle (COP) defects, and scratches caused by polishing.